The present invention relates to a double-sided display device and a method of fabricating the same.
The present application claims priority from Japanese Patent Application No. 2004-067169, the disclosure of which is incorporated herein by reference.
Various types of self-emitting flat panel display devices such as an organic electroluminescence (EL) display device, a plasma display panel (PDP), and a field emission display (FED) have recently been developed. In these display devices, a display is formed by arranging self-emitting elements on a substrate. Therefore, the display devices have attracted attention as display devices which are advantageous over liquid crystal displays requiring a backlight in possibility of reduction of power consumption as well as of thickness.
Moreover, in the self-emitting flat panel display devices, substrates of two displays are bonded to each other so that their light-emitting sides are oriented outward. As a result, a double-sided display device enabling the display on both sides can be formed. In Japanese Patent Application Laid-Open Nos. Hei 8-153586 and 2004-14316, a double-sided display device formed by an organic EL display device is disclosed. In the case of the organic EL display device, a sealing structure for blocking organic EL elements formed on a substrate from the outside air is required because the organic EL elements have a property of deteriorating its display performance when they are exposed to the outside air containing moisture and the like. According to the above-described conventional techniques, substrates, each being a transparent substrate on which an organic EL element is formed, are bonded to each other so that their faces carrying the organic EL elements face each other. In this manner, the organic EL elements are sealed between the pair of substrates. A display plane is formed on the bottom face side of each of the substrates so that the display planes of the respective substrates are oriented in the opposite directions, thereby achieving the display on both sides.
In a self-emitting display device such as the above-described organic EL display device, the following structure is used. A lead wiring section is formed on an end of a substrate by a lead wiring led from a self-emitting element area in a sealing structure so as to connect a driving circuit component or a wiring substrate for supplying a driving signal to the self-emitting element area. With such a structure, the lead wiring section and a connecting section such as the driving circuit component or the wiring substrate are electrically connected with each other.
On the other hand, as the above-described conventional technique, if a pair of substrates, on which self-emitting element areas are respectively formed, are bonded to each other so that their faces carrying the self-emitting element areas face each other, lead wiring sections, each formed in an end of each of the substrates, are arranged so as to be opposed to each other. Accordingly, there arises a problem that, when one of the lead wiring sections is connected to the driving circuit component, the wiring substrate, or the like, the other lead wiring section interferes in connection, making the connecting operation difficult.
In order to avoid such interference, the substrates are bonded to each other so that their lead wiring sections are oriented in different directions; the lead wiring section of one of the substrates does not overlap the lead wiring section of the other substrate. With such a structure, however, the lead wiring sections project in different directions. Therefore, the entire panel area is increased to correspondingly increase the space occupied by the display device when the display device is placed. Accordingly, there arises a problem that such a display device does not satisfy the requirement of reduction in size, which is requested for mounting it on small electronic equipment.
Moreover, with the structure in which the lead wiring sections on a pair of substrates project in different directions, a plurality of driving circuit components, wiring substrates or the like, connected to the lead wiring sections are correspondingly required, or a large wiring substrate for covering the different directions of projections is required. Therefore, an excessively large space in electronic equipment is occupied by the plurality of driving circuit components, wiring substrates or the like. Also in this regard, there arises the problem that the requirement of reduction in size is not satisfied.